Model driven estimation of faulted area in electric distribution systems

ABSTRACT

A system for estimating faulted area in an electric distribution system. The system includes a database storing input data, a fault detection module to estimate, based on the input data, if a new faulted area estimation process is required, a condition estimation module to estimate condition of metered protective devices, un-metered protective devices, and metered devices (PMDs), an upstream to downstream module to assess condition of each metered protective device, un-metered protective device, and metered device (PMD), starting from a feeder circuit breaker towards feeder downstream, to estimate a tripped protective device and a last metered device upstream of a fault, and a downstream to upstream module configured to assess outaged electric loads or elements towards network upstream to find the common interrupting protective device.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. patent applicationSer. No. 16/163,493, filed Oct. 17, 2018, which claims priority to U.S.Application No. 62/577,938, filed Oct. 27, 2017, and U.S. ApplicationNo. 62/577,953, filed Oct. 27, 2017, the entire contents and disclosuresof which are hereby incorporated by reference.

FIELD OF THE INVENTION

The claimed invention relates to estimating faulted area within anelectric distribution system and more particularly to system and methodfor estimating faulted area within an electric distribution system usingoffline model and online data.

BACKGROUND OF THE INVENTION

In a typical electric distribution system, several feeders originatedfrom one or more substations supplying electricity to the customers. Ina power outage, electric distribution system faulted area estimation,isolation and service restoration is one of the key applications withinan advanced distribution management system (ADMS). Locating fault indistribution system often has two aspects. The first aspect is todetermine the tripped protective device and corresponding faulted areawhile another aspect is to estimate the distance/impedance/reactancebetween the fault location and the location where a waveform recordingdevice is installed within a distribution feeder, i.e. typically at thefeeder substation. Considering the nature of distribution feeder with amain and several laterals, there are multiple locations within adistribution feeder that can have the same distance/impedance/reactance.The most probable fault locations are the locations within the estimatedfaulted area.

In a typical electric distribution system, several feeders originatedfrom one or more substations supply electricity to the customers. Eachfeeder is protected and monitored through several devices, includingmetered protective devices, un-metered protective devices, and metereddevices, all of which will be collectively referred to in thisdisclosure as protective or metered devices (PMDs). These feeders aretypically interconnected at one or more locations through normallyopened switches allowing temporary restoration for some loads ifpossible. FIGS. 1A and 1B illustrate an exemplary simple distributionsystem 100 with three feeders 104, 106, 108 originated from onesubstation 102 (FIG. 1B). As shown in FIG. 1B, some of monitoring andprotective related data at each substation can be collected andtransferred to distribution control center using a remote terminal unit(RTU) 110. One of the main applications used in control center is outagemanagement system (OMS) 120 (FIG. 1A). In current distributionmanagement system, OMS can utilize network connectivity data, onlinedata transmitted by RTUs, outages reported through customer calls andfeedback received from crews in the field through Workforce ManagementSystem 130 to detect incidents, find fault locations, and determineisolation and restoration steps.

One of the key functionality of OMS application is locating fault. Inpower industry, fault location is perceived as an application where thelocation of the fault is estimated typically using voltage and currentwaveforms or values collected at the point of interconnection of feederto the substation. In a typical fault scenario, multiple locations wouldbe estimated as point of fault due to the nature of distribution feedernetwork connectivity. Hence, another application is required to filterout the potential fault locations based on PMD, customer calls and crewfeedback data collected through the field.

It is therefore desirable to provide system and method for improvementsin estimating faulted area within an electric distribution system, andthat provide advantages heretofore unknown in the art.

SUMMARY OF THE INVENTION

Provided herein are exemplary embodiments of systems, devices andmethods for estimating faulted area within an electric distributionsystem.

This operation, referred to as faulted area estimation, can beindependently used to predict tripped protective device and the areawhere the fault location lies to dispatch crews to investigate theissue, and at the same time perform temporary restoration. The presentdisclosure describes a new system, method and model to perform faultedarea estimation.

In some embodiments, the present disclosure includes a system forestimating faulted area in an electric distribution system. The systemincludes a database storing input data, a fault detection module todetermine, based on the input data, if a new faulted area estimationprocess is required, a condition estimation module to estimate conditionof metered protective devices, un-metered protective devices, andmetered devices, all of which will be collectively referred to in thisdisclosure as protective or metered devices (PMDs), an upstream todownstream module to assess condition of each PMD, starting from afeeder circuit breaker towards feeder downstream, to estimate a trippedprotective device and a last metered device upstream of a fault, and adownstream to upstream module configured to assess outaged electricloads or elements towards network upstream to find the commoninterrupting protective device.

In some embodiments, the present disclosure includes a method forestimating faulted area in an electric distribution system. The methodmay include estimating, by a fault detection module, based on one ormore input data, if a new faulted area estimation process is required;estimating, by a condition estimation module, condition of un-meteredprotective devices and condition of metered protective devices;assessing, by an upstream to downstream module, condition of eachun-metered protective device and condition of each metered protectivedevice, starting from a feeder circuit breaker towards feederdownstream, to estimate a tripped protective device and a last metereddevice upstream of a fault; and assessing, by a downstream to upstreammodule, outaged electric loads and elements towards network upstream tofind the common interrupting protective device.

Other features and advantages of the present invention will be or willbecome apparent to one with skill in the art upon examination of thefollowing figures and detailed description, which illustrate, by way ofexamples, the principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be better understood by referring to thefollowing figures. The components in the figures are not necessarily toscale, emphasis instead being placed upon illustrating the principles ofthe disclosure. In the figures, like reference numerals designatecorresponding parts throughout the different views.

FIG. 1A illustrates a exemplary applications in an electric distributionsystem, according to an embodiment of the invention

FIG. 1B illustrates an exemplary simple electric distribution system,according to an embodiment of the invention.

FIG. 2 illustrates an exemplary process of faulted area estimation,according to an embodiment of the invention.

FIG. 3 illustrates exemplary high-level diagram of a conditionestimator, according to an embodiment of the invention.

FIGS. 4A and 4B illustrate an exemplary parent rule judgments process,according to an embodiment of the invention.

FIGS. 5A and 5B illustrate an exemplary child rule judgments process,according to an embodiment of the invention.

FIG. 6 illustrates an exemplary system diagram of a system for faultedarea estimation in an electric distribution system, according to anembodiment of the invention.

FIG. 7 illustrates exemplary system or apparatus in which processes ofthe present disclosure can be implemented, according to an embodiment ofthe invention.

DETAILED DESCRIPTION

The below described figures illustrate the described invention andmethod of use in at least one of its preferred, best mode embodiment,which is further defined in detail in the following description. Thosehaving ordinary skill in the art may be able to make alterations andmodifications to what is described herein without departing from itsspirit and scope. While this invention is susceptible of embodiment inmany different forms, there is shown in the drawings and will herein bedescribed in detail a preferred embodiment of the invention with theunderstanding that the present disclosure is to be considered as anexemplification of the principles of the invention and is not intendedto limit the broad aspect of the invention to the embodimentillustrated. All features, elements, components, functions, and stepsdescribed with respect to any embodiment provided herein are intended tobe freely combinable and substitutable with those from any otherembodiment unless otherwise stated. Therefore, it should be understoodthat what is illustrated is set forth only for the purposes of exampleand should not be taken as a limitation on the scope of the presentinvention.

Turning to the drawings, FIGS. 1 to 7 illustrate exemplary embodimentsof systems and methods for estimating faulted area in an electricdistribution system, which may be generally referred to as Faulted AreaEstimation. The faulted area may be bounded to one or a combination ofprotective devices, meters and electrical loads. The present disclosureutilizes both online and offline data to estimate the faulted area. Insome embodiments, the present disclosure may not use recorded waveformsby protective relays or fault recorders. However, the resulted area canbe utilized to limit possible fault locations derived from the recordedwaveform analysis.

Generally, the offline data may include the model of an electricdistribution system including network connectivity data and high-leveloperational behavior of protective devices such as observability, faultinterruptability, reclosability and sectionalizing capability. Onlinedata that can be utilized may include online condition data of theobservant electric devices, fault indication, reclosing stage, crewcondition feedback and customer calls. “Condition” is defined herein asan extended status of a metered protective device, un-metered protectivedevice, and metered device (PMD), which holds any value within thecondition range, e.g., Energized, Close_Hot, Close, Close_Dead,Open_Hot, Open, Open_Dead, and Unknown. Condition estimation of electricdistribution devices especially unmetered protective devices isessential to perform fault management applications such as faulted areaprediction and accurate fault locating.

In some embodiments, upon detection of fault, a fault detection logic ormodule determines if a new faulted area estimation process is requiredor the fault indication belongs to an existing faulted area estimationprocess. Each faulted area estimation process handles a feeder within adistribution system. For each faulted area estimation process, a statemachine may be established to assess online data from pre-faultcondition to the present. Upstream to downstream evaluation may beperformed by assessing each PMD, starting from feeder circuit breakertowards feeder downstream based on its behavior and the latest onlinedata to estimate the tripped protective device as well as the lastmetered device upstream of the fault. Downstream to upstream evaluationmay be performed by assessing the outaged electric loads/elementstowards network upstream to find the common interrupting protectivedevice. Results of both evaluations may be merged at the end to predicta faulted area.

As used herein, a logic or module may be one or more software programsor may be part of a software program. In some embodiments, a logic ormodule may include hardware component.

A condition estimator described herein may be applicable to distributionfeeders that are operated radially. Nevertheless, the feeder can havevarious types of distributed energy resources integrated as far asislanded operation may not be allowed. In applications where each radialcircuit is fed through a ring (looped) circuit, the present disclosurecan still be applied to the radial portion. The present disclosure maybe applied to single or multiphase system.

Turning to FIG. 2, an exemplary process 200 of faulted area estimationis illustrated, according to some embodiments of the disclosure.Generally, online input data 210 may be utilized to detect fault, atFault Detection logic or module 230. Once a new fault is detected, a newfaulted area estimation process is generated. However, if the databelongs to an existing faulted area estimation process, only theexisting process will be executed and resulted faulted area may beupdated. Each faulted area estimation process may represent a faultedfeeder and a fault. In the case of a faulted feeder where the faultedarea or location is confirmed by a system operator, any new faultindication within the same feeder but outside of the confirmed faultedarea may result in a new faulted area estimation process which excludesthe confirmed faulted area. Each faulted area estimation process maymaintain all the offline and online data relevant to the faulted feeder.Description of each component is described further below.

Offline Input Data

In some embodiments, offline input data 220 may include PMD data andelectric network connectivity data.

PMD Data:

In some embodiments, PMD data may include a list of metered protectivedevices, un-metered protective devices, and metered devices (PMDs) suchas circuit breakers, reclosers, fuses, distribution transformer meters,fault indicators, smart meters, etc. In addition, it may hold high levelcharacteristics of protective devices including normal operation status(Open/Close), observability (if condition is availabledirectly/indirectly, it is observable), and type (non-interrupter, faultinterrupter, recloser, switch, sectionalizer, double-throw switch orload). If load or a combination of loads is not metered, a virtualnon-observable PMD (Type Load) is considered to represent load conditionin the Condition Estimator, which will be described in more detailbelow.

Connectivity Data:

In some embodiments, connectivity data may include information of adistribution feeder, in a suitable format, to define distribution busesor nodes especially those that are connected to PMDs, branches betweentwo nodes and shunt elements such as nodes. In some embodiments, for thesake of simplicity, connectivity data may not include de-energized orout-of-service elements. This means that, connectivity data shouldrepresent the feeder before fault occurrence. However, it is possible toinclude them and enhance the condition estimator logic of the presentdisclosure to account for such elements. For example, connectivity datamay be a list of nodes. Each node knows its connectivity data to itsconnected nodes including the information of branches and PMDs inbetween. In addition, each node may include the information of theconnected shunt devices to the node.

Online Input Data

In some embodiments, online input data 210 may include condition, faultindication, reclosing stage (or reclosing shot, which may be anindicator typically a number to show how many times recloser hasinterrupted and reclosed after fault occurrence), crew feedback andcustomer call.

Condition

This data may indicate condition for any observable PMD along with timestamp of the last measurement. In some embodiments, possible conditionsmay be: Energized, Close_Hot, Close, Close_Dead, Open_Hot, Open,Open_Dead, and Unknown. These conditions are defined below.

Energized: PMD carries current/power above a minimum current threshold.This threshold may be set so as to ensure that some level of load iscarried out through the PMD. For instance, this threshold can be set to5% of the rated current at the point of measurement.

Close_Hot: PMD is closed and is hot (has voltage), i.e., the voltage ismore than a minimum voltage threshold. For instance, this threshold canbe set to 5% of the rated voltage at the point of measurement.

Close: PMD is closed but there is no data available regarding voltage orcurrent amount, for example due to lack of sensory, or the current valueis not high enough to make any judgment. It should be noted that thecondition of uninterruptable PMDs may be one of the above, e.g.,Energized, Close_Hot or Close. In addition, the normal operatingcondition of uninterruptable PMDs is set to Close.

Close_Dead: PMD is closed but voltage is less than a minimum voltagethreshold.

Open_Hot: PMD is open and its upstream terminal is hot (has voltage).Upstream terminal is the terminal that is towards the feeder circuitbreaker. In the case of normally open Tie PMDs, PMD is hot if any ofboth terminals are hot. Tie PMD is a protective or metered device thatconnects two electric distribution feeders together.

Open: PMD is open but there is no data available regarding voltageamount, due to for example the lack of sensory, or the voltage value isnot high enough to make any judgment.

Open_Dead: PMD is open and voltage is less than a minimum voltagethreshold.

Unknown: PMD is not observable or condition estimation is not possibletemporarily.

It should be noted that if a PMD condition is “Energized”, it is at thesame time Close_Hot or Close. The Condition estimated is a guaranteedstate based on the available data.

In the case of single-phase tripping or when not all three phases areimpacted due to fault clearance, only impacted phases may be employed toestimate condition. In addition, the condition definition can beextended for more than two terminal devices such as double-throw switch.

Crew_Feedback:

The feedback may include condition for unobservable PMDs provided bycrew in the field along with reporting time stamp. For any PMD, theonline condition may be the most recent data between metered Conditionand Crew_Feedback based on their time stamps.

Fault Indication:

Protective or metering devices with communication capability cantransmit fault detection information in various forms such as an eventfor each detection or a counter value that increments for any new faultdetection.

Customer Calls:

In today's modern distribution automation system, customer calls areavailable for outage management system to be used as part of faultlocation, isolation and service restoration. In the present disclosure,each customer may be modeled as part of connectivity data and representa PMD. Any customer call in the form of an event or other forms may beutilized to initiate or update a faulted area estimation process withinthe present disclosure.

Output Data

Faulted Area Estimation:

A main purpose of the present disclosure is to estimate a faulted area.In the present disclosure, Faulted Area may be a region within adistribution feeder that starts by a PMD called “Start PMD” and endswith one or more PMDs called “End PMDs”. All the PMDs in between arereferred to under “Middle PMDs”.

Fault Detection

Still referring to FIG. 2, online input data 210 may be fed into a FaultDetection module 230. At each time step (e.g., every few seconds), theonline input data may be scanned. Any change detected within (1)Condition, (2) Fault Indication, and (3) Customer call data may becollected to be assessed. For any change, it is determined whether thedata change belongs to an existing faulted area estimation process or anew faulted area estimation process should be created. In someembodiments, this may be done by the following steps.

Step 1: The feeder of the PMD indicating a fault is found. If the foundfeeder does not have an existing faulted area estimation process, createa new one. Otherwise:

Step 2: If the found feeder has an existing faulted area estimationprocess with confirmed faulted area location, then:

Step 2a: Find the outaged area. Outaged area is the list of all PMDsincluding electric loads that are de-energized due to the fault.

Step 2b: If the PMD is not within the outaged area, create a new faultedarea estimation process. Otherwise, ignore the fault indication and nofaulted area estimation update is required.

State Machine

In some embodiments, each faulted area estimation process is associatedwith a state machine 250 which has two main states: 1—Pre-fault, and2—Post-fault. Once a state machine is created, it may be set topre-fault condition. In pre-fault condition, archived online data justprior to fault detection (at 230) may be utilized to run conditionestimation (at 252). The state machine 250 may stay in pre-faultcondition once, and then may switch to post-fault condition. Inpost-fault state, post-fault online data may be utilized at every timestep to estimate the faulted area. At this state, Downstream-to-upstreamevaluation (at 256) may be performed for any new customer call orcondition change. Whereas, Upstream-to-downstream evaluation (at 254)may be performed for any new fault indication or condition change. Toavoid faulted area estimation process during fault condition or anytransitional data, faulted area estimation process may only be performedwhen the online data related to the faulted area estimation process isconsistent for a few consecutive time steps that is set by default. Insome embodiments, the default may be two.

In some embodiments, a time step may be about a few seconds that isrecommended to be greater than half of the maximum fault clearing timeof any metered protective device with the distribution system. Even ifthis condition is not met, the estimated faulted area would be incorrectmomentarily and will be updated with correct faulted area when all theonline data to the faulted area estimation process belongs to thepost-fault state. Each evaluation may result into one or multipleestimated faulted areas. Once both evaluations have been performed, theresulted estimated faulted areas will be merged if possible (at 258) toestimate a faulted area.

Condition Estimation

As stated above, condition estimation (at 252) may be performed as partof the state machine 250. “Condition” is defined as an extended statusof a PMD which holds any value within the condition range, e.g.,Energized, Close-Hot, Close, Close-Dead, Open_Hot, Open, Open_Dead, andUnknown. Condition estimation is a process of estimating condition ofun-observant (un-metered) protective devices as well as condition ofobservant (metered) PMDs with old time stamps. The condition estimatormay take full benefit of measured data within distribution system toenhance the visibility of the system for the application of faultmanagement system while it minimizes the amount of data required to betransferred through communication system. Although the process ofcondition estimation is described herein as for use in faulted areaestimation in an electric distribution system, it also has otherapplications beside the present disclosure. See the Condition Estimatorsection in this present disclosure for further detail.

Upstream to Downstream Evaluation

In some embodiments, Upstream to Downstream Evaluation (at 254) isanother process of the state machine 250. This evaluation is explainedby the following steps.

Step 1: Condition estimation (at 252) is executed for the latest onlinedata. See the Condition Estimator section in this present disclosure forfurther detail.

Step 2: The following lists are created:

List (a), FaultDetectors: This list may include all PMDs that indicatenew fault either directly through fault indication or they areinterruptible and their conditions have changed to one form of Openwhile they were close prior to fault.

List (b), Close_Deads: This list may include all PMDs that haveClose_Dead condition while they had Energized or Close_Hot conditionprior to fault.

Step 3: If the list of FaultDetectors is empty, find the most commoninterruptible PMD parent of PMDs listed in Close_Deads. If found, thisPMD is a candidate PMD for faulted area estimation. Go to Step [0062].

Step 4: Start from the feeder Circuit Breaker/PMD, check each PMD byanalyzing the network connectivity towards downstream appreciatingpre-fault PMD condition, i.e., stop at a PMD with any form of Open(Open_Hot, Open, Open_Dead) condition while pass through a PMD with anyform of close (Energized, Close_Hot, Close, Close_Dead) or Unknownconditions. The last PMD found to be in the list of FaultDetectors is acandidate for the start of faulted area estimation.

Step 5: If a candidate PMD is found, revise the candidate PMD based onreclosing information as following:

Step 5a: If the candidate PMD is not Interruptible but capable ofdetecting fault, and it is downstream of a recloser and upstream ofsectionalizer, use upstream recloser for the following steps instead ofthe candidate PMD if it is not open of any form and completed possiblereclosing stages. Otherwise, continue with the original candidate PMD.

Step 5b: If the candidate PMD is reclosable, and it is close of anyform, and either it has not reclosed or has completed all possiblereclosing stages, find the following lists:

5b.i: PMD_Children: all immediate PMDs downstream of the candidate PMD.

5b.ii: Interruptible_PMD_Children: all immediate interruptible PMDsdownstream of the candidate PMD.

Then,

5b.iii: If PMD candidate has not reclosed at all, replace candidate PMDwith all PMDs in Interruptible_PMD_Children list.

5b.iv: If PMD candidate has completed all possible reclosing stages,replace candidate PMD with its downstream sectionalizer.

Step 6: For each candidate PMD found from the previous step, a faultedarea is created starting from each PMD. Then, for each area, the otherends (boundary) PMDs and Middle PMDs are determined as following steps:

Step 6a: If start PMD is Open, or it is reclosable and at least reclosedonce, or it is sectionalizer, the other ends of estimated faulted areaare the interruptible PMD children of the start PMD. Otherwise:

Step 6b: the other ends of the estimated faulted area are the mostdownstream PMD/loads downstream of the Start PMD where there is no pathwith Energized or Close_Hot PMD in between. Middle PMDs are all PMDsexclusively between Start PMD and End PMDs.

Downstream to Upstream Evaluation

In some embodiments, the Downstream to Upstream Evaluation (at 256) ofthe state machine 250 may include the following steps.

Step 1: Condition estimation (at 252) is executed for the latest onlinedata. See the Condition Estimator section in this present disclosure forfurther detail.

Step 2: A List of all outaged customers (PMDs) relevant to the faultedfeeder since fault has been detected is created.

Step 3: For each customer in the list created in Step 2, if theimmediate PMD parent has a condition of Open in any form, Add the PMDparent to the list of candidate PMDs. Further, the customer may beremoved from the outaged customer list.

Step 4: If the outaged customer list is not empty, find the most commoninterruptible PMD parent of all the outaged customers in the list withinthe faulted feeder. If found, this PMD is added to the list of candidatePMDs.

Step 5: If no common interruptible PMD parent found in the previousstep, all outaged customers are added to the list of candidate PMDs.

Step 6: For each candidate PMD found from the previous Step 5, a faultedarea is created starting from each PMD. Then, for each estimated faultedarea, the other ends (boundary) are determined as in the followingsteps.

Step 6a: If start PMD is Open, or it is reclosable and at least reclosedonce, or it is sectionalizer, the other ends of estimated faulted areaare the interruptible PMD children of the start PMD. Otherwise:

Step 6b: the other ends of the estimated faulted area are the mostdownstream PMD/loads downstream of the Start PMD.

Merge Estimated Faulted Areas

As shown in FIG. 2, estimated faulted areas found using Upstream toDownstream (at 254) and Downstream to Upstream (at 256) evaluations maybe merged (at 258) to estimate a faulted area. The following steps maybe performed at merging 258.

Step 1: First, faulted areas from both evaluations are combined.

Step 2: Among combined faulted areas with the same Start PMD, keep thefirst location and remove the rest.

Step 3: Check all faulted areas. If Start and Ends of a faulted area(Area A) is within the Middles and Ends of another faulted area (AreaB), remove Area A. In other words, since Area A is a subset of Area B,the process picks Area B, which is more comprehensive.

It should be noted that the present disclosure is not limited to singlefeeder but covers a large distribution system with multiple feeders. Thefeeder connectivity is not static and can change dynamically duringday-to-day operation. This is advantageous over existing solutions thatare based on a single feeder with static configuration. The presentdisclosure may advantageously utilize all possible online data from:protective devices, fault indicators, meters, customer calls along withmodel data especially high level behavior of protective devices toachieve a more precise location.

In some embodiments, due to the advantageous use of a conditionestimator, there is no stringent requirement on the communication systemand measurement synchronization and time stamping accuracy.

It should also be noted that the present disclosure may handle multiplefaults within a distribution feeder with a reasonable practical timeintervals among them assuming that all old faults are confirmed withinthe faulted feeder.

In some embodiments, the present disclosure may handle single phase andthree phase systems.

Condition Estimator

Referring to FIG. 3, an exemplary high-level diagram of a conditionestimator 300 is illustrated. Condition estimation of electricdistribution devices, especially unmetered protective devices, isessential to perform fault management applications such as faulted areaestimation and accurate fault location. As stated above, “Condition” isused in the present disclosure as an extended status of a PMD whichholds any value within the condition range i.e., Energized, Close-Hot,Close, Close-Dead, Open_Hot, Open, Open_Dead, Unknown. The conditionestimator takes full benefit of measured data within distribution systemto enhance the visibility of the system for the application of faultmanagement system while it minimizes the amount of data required to betransferred through communication system.

Generally, inputs to the system of the present disclosure as describedabove include online condition data of the observant devices, crewfeedback, as well as offline data including network connectivity dataand high level operational behavior of protective devices such asobservability, fault interruptability and switching capability.Condition can be determined at the location of protective or meteringdevices and inputted to the condition estimator while raw data such asswitching status of circuit breaker, terminal voltage or through currentcan be provided to condition estimator where the input condition isdetermined at the estimator location. In various embodiments, input dataare provided with a time stamp. In some embodiments, synchronizationprecision requirements may not be stringent for the application of faultmanagement system. Outputs from the system may include estimatedconditions of unobservant devices as well as observant devices witholder time stamp.

The condition estimator 300 may include an iterative technique thatexamines several electrical rules for each PMD within a distributionfeeder as compared to its neighboring devices. In some embodiments, theestimator 300 may consider the last measurement for each data, type ofprotective device and network connectivity information to estimate (1)Condition of unobservant devices, and (2) Condition of observant deviceswith older time stamps.

The condition estimator may be applicable to distribution feeders thatare operated radially. Nevertheless, the feeder can have various typesof distributed energy resources integrated as far as islanded operationis not allowed. In applications where each radial circuit is fed througha ring (looped) circuit, the present disclosure can be still applied tothe radial portion. It should be noted that the present disclosure canbe applied to single or multiphase system.

The condition estimator 300 may receive offline input data 310 andonline input data 320 and output estimated conditions 390.

Condition Estimator Input Data Condition Estimator Offline Input Data

In some embodiments, offline input data 310 for the condition estimator300 may include PMD Data: This may include a list of PMDs such ascircuit breakers, reclosers, fuses, distribution transformer meters,fault indicators, smart meters and etc. In addition, it may hold highlevel characteristics of protective devices including normal operationstatus (Open/Close), observability (if condition is availabledirectly/indirectly, it is observable), Type: (non-interrupter, faultinterrupter, switch, sectionalizer, double-throw switch or load). Ifload or a combination of loads is not metered, a virtual non-observablePMD (Type Load) is considered to represent load condition in theinvented Condition Estimator.

In some embodiments, offline input data 310 for the condition estimator300 may also include Connectivity Data: This data may include sufficientinformation of a distribution feeder in any form to define distributionbuses or nodes especially those that are connected to PMDs, branchesbetween two nodes and shunt elements such as loads. In some embodiments,for the sake of simplicity, de-energized or out of service elements maynot be part of the connectivity data. This means that, connectivity datashould represent the feeder before fault occurrence. However, it may bepossible to include them and enhance the invented condition estimatorlogic to account for such elements.

Condition Estimator Online Input Data Condition

In some embodiments, online input data 320 for the condition estimator300 may include condition for any observable PMD along with time stampof the last measurement. Possible conditions may be {Energized,Close_Hot, Close, Close_Dead, Open_Hot, Open, Open_Dead, and Unknown} asdefined below.

Energized:

PMD carries current/power above a minimum current threshold. Thisthreshold may be set properly to ensure that some level of load iscarried out through the PMD. For instance, this threshold can be set to5% of the rated current at the point of measurement.

Close_Hot:

PMD is closed and is hot (has voltage), i.e., the voltage is more than aminimum voltage threshold. For instance, this threshold can be set to 5%of the rated voltage at the point of measurement.

Close:

PMD is closed but there is no data available regarding voltage orcurrent amount due to lack of sensory, or the current value is not highenough to make any judgment. It is important to note that the conditionof uninterruptable PMDs should be one of the above e.g., Energized,Close_Hot or Close. In addition, the normal operating condition ofuninterruptable PMDs is set to Close.

Close_Dead:

PMD is closed but voltage is less than a minimum voltage threshold.

Open_Hot:

PMD is open and its upstream terminal is hot (has voltage). Upstreamterminal is the terminal that is towards the feeder circuit breaker. Incase of normally open Tie PMDs, PMD is hot if any of both terminals arehot. Tie PMD is a protective metered or unmetered device that connectstwo electric distribution feeders together.

Open:

PMD is open but there is no data available regarding voltage amount dueto the lack of sensory or the voltage value is not high enough to makeany judgment.

Open_Dead:

PMD is open and voltage is less than a minimum voltage threshold.

Unknown:

PMD is not observable or condition estimation is not possibletemporarily.

It should be noted that if a PMD condition is Energized, it is at thesame time Close_Hot or Close. The Condition estimated is a guaranteedstate based on the available data.

In the case of single-phase tripping or when not all three phases areimpacted due to fault clearance, only impacted phases may be employed toestimate condition. In addition, the condition definition can beextended for more than two terminal devices such as double-throw switch.

Crew_Feedback

In some embodiments, online input data 320 for the condition estimator300 may also include condition for unobservable PMDs provided by crew inthe field along with reporting time stamp. For any PMD, the onlinecondition may be the most recent data between metered Condition andCrew_Feedback based on their time stamps.

Condition Estimator Output Data

Generally, output data of the condition estimator 300 include estimatedconditions 390 for all PMDs. For an observable PMD with data belong toolder time stamp, the condition estimator 300 may estimate a correctedcondition using neighboring PMDs data with newer time stamp if possible.Condition is defined as above.

The estimated conditions 390 may include time stamps.

Parent and Child Tables Determination

In some embodiments, parent and child PMD tables 330 may be determined,or created, for use by the condition estimator 300. The term Childrefers to downstream PMDs while the term Parent refers to upstream PMD.It is important to note here that the use of parent and child PMD tablesmay be optional. Connectivity data can be utilized in any form todetermine upstream/downstream (parent/child) PMDs. As shown in FIG. 3,only offline data 310 may be required to build tables 330. In theprocess of condition estimation, tables 330 are generated once and usedin execution as far as the feeder connectivity data has not changed.Utilizing PMD child and parent tables, grand child or grandparent PMDscan be also identified and utilized.

Child Table

The network connectivity data may be analyzed starting from the feedercircuit breaker. For each PMD, the immediate downstream PMD(s) may bedetermined. These PMD(s) may be recorded in the PMD child table, as partof tables 330. The entire network is analyzed until all PMDs areanalyzed. Using this child table, it is possible to simply determinechild PMDs for any PMD.

Parent Table

In an aspect, a parent table may be derived from the child table.Analyze the entire PMD child list. For each child PMD, record upstreamor parent PMD in the PMD parent table, as part of tables 330. The feederCB (PMD) does not have any parent. Using this parent table, it ispossible to simply determine parent PMD(s) for any PMD. In typicalradial distribution system, most PMDs have only one parent PMD whileTied PMDs which are normally open have two parents.

Condition Estimation

The condition estimation may start at 340. At each execution of thecondition estimator 300, if parent and child tables are available, theprocess of estimation may start by initializing PMD conditions, at 342.

Initialization:

At 342, all observable PMD conditions may be initialized with latestonline data including condition and time stamp. All unobservable PMDconditions may be initialized with either (1) normal operating status incase of first time initialization, or (2) latest condition estimated inthe last time step. For any PMD (type=load), initial condition may beset to Unknown in case of first time initialization, otherwise latestestimated condition may be used. For any PMD, if Crew_Feedback isavailable and has the newer time stamp than the time stamp of lastmeasured condition, PMD condition and time stamp would be initializedwith Crew_Feedback and its time stamp, respectively.

Apply Parent and Child PMD Rules:

At each iteration 344 of condition estimation, parent and child rules,as defined below and in FIGS. 4A-4B and 5A-5B, may be applied. Bothchild and parent tables may be used for the judgment processes describedin the following sections. Having two tables make it advantageouslyfaster to find each PMD's children or parents. For each set ofparent-children, first the child with (1) one parent, (2) newest timestamp, (3) Condition within {Energized, Close_Hot, Close_Dead, Open_Hotor Open_Dead} and finally (4) lowest condition may be found. Based onthese criteria, if more than one child is found, anyone can be selected.For each parent-children set, this child is defined as the Ruling Child.If the Ruling Child has a newer time stamp than parent, parent judgmentrules will be applied as followings. It is important to note here thatParent Judgment cannot be applied in case of Multi-Parent case. In caseof distribution feeders that are operated radially, each PMD will haveonly one parent.

Parent Judgment Rules

The condition estimator 300 may apply parent judgment rules to updatethe condition of a parent PMD based on the condition of its RulingChild. FIGS. 4A and 4B illustrate an exemplary process 400 of applyingparent judgment rules. In some embodiments, the following Rules may beapplied.

Rule 1. Major judgment is possible only if Ruling Child is found.Otherwise, minor judgment may be applicable as defined in Rule 6 below.A major judgment means when the condition of a child may considerablydictate its parent's condition. In contrast, a minor judgment means whenthe condition of a child may not considerably change or dictate itsparent's condition.

Rule 2. Major Judgment is possible only if Ruling Child has a newer timestamp than its parent. Otherwise, minor judgment may be applicable asdefined in Rule 8 below.

Rule 3. If Ruling Child is Energized, set Parent to Energized.

Rule 4. If Ruling Child is Close_Hot or Open_Hot, set Parent toClose_Hot.

Rule 5. If Ruing Child is Open_Dead or Close_Dead, if Parent isuninterruptible, set Parent to Close_Dead, otherwise if Parent isinterruptible and has at least one Grandparent with Energized orClose_Hot condition, set parent condition to Open_Hot; otherwise setparent to Unknown.

Rule 6. In the case of no Ruling Child PMD, among all Child PMDs withUnknown status excluding load PMDs, find the child PMD with latest timestamp. If the child has a newer time stamp than its parent, if parent isinterruptible, set Parent condition to Unknown, otherwise set to Close.

Rule 7. When any of Rules 3, 4, 5 or 6 is applied, update Parent timestamp with Child time stamp.

Rule 8. If Child and Parent time stamps are equal and parent is notmetered while child condition is energized, set parent condition toEnergized.

Child Judgment Rules

For each parent-children set, child rules as defined below may beapplied after parent rules have been applied. The condition estimator300 may apply child judgment rules to update the condition of a childPMD based on the condition of its parent PMD. FIGS. 5A and 5B illustratean exemplary process 500 of applying child judgment rules. In someembodiments, the following Rules may be applied.

Rule 9. Judgment is possible only if parent has an equal or newer timestamp than its child. The equal condition will make the parent dominantin case of parent-child conflict. It is possible to make child dominantas well. However, in distribution system, it is expected to have betterand more reliable measurement and data communication for Parent PMD ascompared to Child PMDs.

Rule 10. If parent's Condition is Energized and parent PMD has only onechild and its condition is not Open of any form i.e., {Open_Hot, Open,Open_Dead}, the child's Condition may be set to “Energized” and its timestamp may be updated with its parent time stamp.

Rule 11. If parent is Energized and has more than one child or it isClose_Hot, promote each child's condition to Hot. If child isinterruptible do not update the time stamp and skip the rest of thisrule. Otherwise, update child's time stamp with parent's time stamp,further, if child's condition is Energized and parent's time stamp isnot equal to child's time stamp, set child's condition to Close_Hot.Condition Promotion to Hot is defined as conversion of {Close,Close_Dead} to Close_Hot and {Open, Open_Dead} to Open_Hot. It should benoted that if a PMD condition is Energized, it is at the same timeClose_Hot or Close. The Condition estimated is a guaranteed state basedon the available data.

Rule 12. If parent has any condition within {Close_Dead, Open_Hot, Open,Open_Dead}, and child has only one parent, de-promote each child'scondition to Dead. Then update its time stamp with parent's time stamp.De-promotion to Dead is defined as a conversion of any condition within{Energized, Close_Hot, Close} to Close_Dead or {Open_Hot, Open} toOpen_Dead.

Extensions

In some embodiments, additional conditions may be used. For example, itmay be possible to consider Close_Hot De-energized, Hot or Deadconditions as part of the condition set and extend the algorithm.However, in certain operations, it may be hard to determine if a PMD isde-energized due to no load condition as compared to fault clearance bydownstream (child) protective device(s) interruption. In addition, itmay not be as practical to have voltage measurement for a PMD whilecurrent measurement or status is not available.

In addition, it may be possible to define Condition as a two-dimensionalstatus. For example, as shown in Table 1, dimension 1 is {Energized,Close, Open, Unknown}, and dimension 2 is {Hot, Dead, Unknown}. In thisdefinition, only the marked options in the table will be available.

TABLE 1 Two Dimension Condition Definition Energized Close Open UnknownHot x x x x Dead x x x Unknown x x x

Check Convergence

Referring again to FIG. 3, after applying parent and child rules, at344, at each iteration of condition estimation, the present and previousestimated conditions of each PMD may be compared. If there is nodifference, convergence is achieved. Otherwise, condition estimation forall PMDs may be repeated. In some embodiments, there may be a limit onthe maximum number of iterations that can be performed. If the maximumnumber of iterations is reached without convergence, the condition andtime stamp of all PMDs may reset to its original values.

Once convergence or maximum iteration is achieved, the process ofcondition estimation 300 may stop at 348, and the estimated conditionsand time stamps may be available as outputs 390.

System Architecture

Turning to FIG. 6, a system diagram of an exemplary system 600 forfaulted area estimation in an electric distribution system, according tosome embodiments of the disclosure, is illustrated. System 600 mayinclude a fault detection module 605, an upstream to downstreamevaluation module 615, a downstream to upstream evaluation module 620, acondition estimator 610, database or storage area 625, and communicationmodule 630. System 600 may reside on a computing system, a single serveror may be distributed. For example, one or more components (e.g., 605,615, 620, 610, etc.) of system 600 may be distributed across variouslocations throughout a network. Each component or module of system 600may communicate with each other and with external entities viacommunication module 630. Each component or module of system 600 mayinclude its own sub-communication module to further facilitate withintra and/or inter-system communication.

Fault detection module 605 determines if a new faulted area estimationprocess is required or the fault indication belongs to an existingfaulted area estimation process. Upstream to downstream evaluationmodule 615 assesses condition of each PMD, starting from feeder circuitbreaker towards feeder downstream based on its behavior and the latestonline data to estimate the tripped protective device as well as thelast metered device upstream of the fault. Downstream to upstreamevaluation module 620 assesses the outaged electric loads/elementstowards network upstream to find the common interrupting protectivedevice. Database or storage area 625 may store various data (e.g.,offline and online input data), tables and condition outputs.

Condition estimator module 610 estimates condition of un-observant(un-metered) protective devices as well as condition of observant(metered) protective devices with old time stamps. The parent and childtable determination modules 611 create parent-child tables for use bythe condition estimator module 610. The rules application modules 612apply parent rules and child rules to estimate conditions of parent andchild PMDs.

FIG. 7 illustrates an exemplary overall system or apparatus 700 in whichprocesses 300, 400, and 500 may be implemented. In accordance withvarious aspects of the disclosure, an element, or any portion of anelement, or any combination of elements may be implemented with aprocessing system 714 that includes one or more processing circuits 704.Processing circuits 704 may include micro-processing circuits,microcontrollers, digital signal processing circuits (DSPs), fieldprogrammable gate arrays (FPGAs), programmable logic devices (PLDs),state machines, gated logic, discrete hardware circuits, and othersuitable hardware configured to perform the various functionalitiesdescribed throughout this disclosure. That is, the processing circuit704 may be used to implement any one or more of the processes describedabove and illustrated in FIGS. 2-5.

In the example of FIG. 7, the processing system 714 may be implementedwith a bus architecture, represented generally by the bus 702. The bus702 may include any number of interconnecting buses and bridgesdepending on the specific application of the processing system 714 andthe overall design constraints. The bus 702 may link various circuitsincluding one or more processing circuits (represented generally by theprocessing circuit 704), the storage device 705, and a machine-readable,processor-readable, processing circuit-readable or computer-readablemedia (represented generally by a non-transitory machine-readable medium706). The bus 702 may also link various other circuits such as timingsources, peripherals, voltage regulators, and power management circuits,which are well known in the art, and therefore, will not be describedany further. The bus interface 708 may provide an interface between bus702 and a transceiver 710. The transceiver 710 may provide a means forcommunicating with various other apparatus over a transmission medium.Depending upon the nature of the apparatus, a user interface 712 (e.g.,keypad, display, speaker, microphone, touchscreen, motion sensor) mayalso be provided.

The processing circuit 704 may be responsible for managing the bus 702and for general processing, including the execution of software storedon the machine-readable medium 706. The software, when executed byprocessing circuit 704, causes processing system 714 to perform thevarious functions described herein for any particular apparatus.Machine-readable medium 706 may also be used for storing data that ismanipulated by processing circuit 704 when executing software.

One or more processing circuits 704 in the processing system may executesoftware or software components. Software shall be construed broadly tomean instructions, instruction sets, code, code segments, program code,programs, subprograms, software modules, applications, softwareapplications, software packages, routines, subroutines, objects,executables, threads of execution, procedures, functions, etc., whetherreferred to as software, firmware, middleware, microcode, hardwaredescription language, or otherwise. A processing circuit may perform thetasks. A code segment may represent a procedure, a function, asubprogram, a program, a routine, a subroutine, a module, a softwarepackage, a class, or any combination of instructions, data structures,or program statements. A code segment may be coupled to another codesegment or a hardware circuit by passing and/or receiving information,data, arguments, parameters, or memory or storage contents. Information,arguments, parameters, data, etc. may be passed, forwarded, ortransmitted via any suitable means including memory sharing, messagepassing, token passing, network transmission, etc.

The software may reside on machine-readable medium 706. Themachine-readable medium 706 may be a non-transitory machine-readablemedium. A non-transitory processing circuit-readable, machine-readableor computer-readable medium includes, by way of example, a magneticstorage device (e.g., solid state drive, hard disk, floppy disk,magnetic strip), an optical disk (e.g., digital versatile disc (DVD),Blu-Ray disc), a smart card, a flash memory device (e.g., a card, astick, or a key drive), RAM, ROM, a programmable ROM (PROM), an erasablePROM (EPROM), an electrically erasable PROM (EEPROM), a register, aremovable disk, a hard disk, a CD-ROM and any other suitable medium forstoring software and/or instructions that may be accessed and read by amachine or computer. The terms “machine-readable medium”,“computer-readable medium”, “processing circuit-readable medium” and/or“processor-readable medium” may include, but are not limited to,non-transitory media such as portable or fixed storage devices, opticalstorage devices, and various other media capable of storing, containingor carrying instruction(s) and/or data. Thus, the various methodsdescribed herein may be fully or partially implemented by instructionsand/or data that may be stored in a “machine-readable medium,”“computer-readable medium,” “processing circuit-readable medium” and/or“processor-readable medium” and executed by one or more processingcircuits, machines and/or devices. The machine-readable medium may alsoinclude, by way of example, a carrier wave, a transmission line, and anyother suitable medium for transmitting software and/or instructions thatmay be accessed and read by a computer.

The machine-readable medium 706 may reside in the processing system 714,external to the processing system 714, or distributed across multipleentities including the processing system 714. The machine-readablemedium 706 may be embodied in a computer program product. By way ofexample, a computer program product may include a machine-readablemedium in packaging materials. Those skilled in the art will recognizehow best to implement the described functionality presented throughoutthis disclosure depending on the particular application and the overalldesign constraints imposed on the overall system.

As used herein and in the appended claims, the singular forms “a”, “an”,and “the” include plural referents unless the context clearly dictatesotherwise.

In the foregoing description and in the figures, like elements areidentified with like reference numerals. The use of “e.g.,” “etc,” and“or” indicates non-exclusive alternatives without limitation, unlessotherwise noted. The use of “including” or “include” means “including,but not limited to,” or “include, but not limited to,” unless otherwisenoted.

As used herein, the term “and/or” placed between a first entity and asecond entity means one of (1) the first entity, (2) the second entity,and (3) the first entity and the second entity. Multiple entities listedwith “and/or” should be construed in the same manner, i.e., “one ormore” of the entities so conjoined. Other entities may optionally bepresent other than the entities specifically identified by the “and/or”clause, whether related or unrelated to those entities specificallyidentified. Thus, as a non-limiting example, a reference to “A and/orB”, when used in conjunction with open-ended language such as“comprising” can refer, in one embodiment, to A only (optionallyincluding entities other than B); in another embodiment, to B only(optionally including entities other than A); in yet another embodiment,to both A and B (optionally including other entities). These entitiesmay refer to elements, actions, structures, steps, operations, values,and the like.

The enablements described above are considered novel over the prior artand are considered critical to the operation of at least one aspect ofthe invention and to the achievement of the above described objectives.The words used in this specification to describe the instant embodimentsare to be understood not only in the sense of their commonly definedmeanings, but to include by special definition in this specification:structure, material or acts beyond the scope of the commonly definedmeanings. Thus if an element can be understood in the context of thisspecification as including more than one meaning, then its use must beunderstood as being generic to all possible meanings supported by thespecification and by the word or words describing the element.

It should be noted that all features, elements, components, functions,and steps described with respect to any embodiment provided herein areintended to be freely combinable and substitutable with those from anyother embodiment. If a certain feature, element, component, function, orstep is described with respect to only one embodiment, then it should beunderstood that that feature, element, component, function, or step canbe used with every other embodiment described herein unless explicitlystated otherwise. This paragraph therefore serves as antecedent basisand written support for the introduction of claims, at any time, thatcombine features, elements, components, functions, and steps fromdifferent embodiments, or that substitute features, elements,components, functions, and steps from one embodiment with those ofanother, even if the following description does not explicitly state, ina particular instance, that such combinations or substitutions arepossible. It is explicitly acknowledged that express recitation of everypossible combination and substitution is overly burdensome, especiallygiven that the permissibility of each and every such combination andsubstitution will be readily recognized by those of ordinary skill inthe art.

In many instances entities are described herein as being coupled toother entities. It should be understood that the terms “coupled” and“connected” (or any of their forms) are used interchangeably herein and,in both cases, are generic to the direct coupling of two entities(without any non-negligible (e.g., parasitic) intervening entities) andthe indirect coupling of two entities (with one or more non-negligibleintervening entities). Where entities are shown as being directlycoupled together, or described as coupled together without descriptionof any intervening entity, it should be understood that those entitiescan be indirectly coupled together as well unless the context clearlydictates otherwise. The definitions of the words or drawing elementsdescribed herein are meant to include not only the combination ofelements which are literally set forth, but all equivalent structure,material or acts for performing substantially the same function insubstantially the same way to obtain substantially the same result. Inthis sense it is therefore contemplated that an equivalent substitutionof two or more elements may be made for any one of the elementsdescribed and its various embodiments or that a single element may besubstituted for two or more elements in a claim.

Changes from the claimed subject matter as viewed by a person withordinary skill in the art, now known or later devised, are expresslycontemplated as being equivalents within the scope intended and itsvarious embodiments. Therefore, obvious substitutions now or later knownto one with ordinary skill in the art are defined to be within the scopeof the defined elements. This disclosure is thus meant to be understoodto include what is specifically illustrated and described above, what isconceptually equivalent, what can be obviously substituted, and alsowhat incorporates the essential ideas.

1. A system for estimating faulted area in an electric distributionsystem, comprising: a database storing one or more input data; a faultdetection module configured to determine, based on the one or more inputdata, if a new faulted area estimation process is required; a conditionestimation module configured to estimate condition of metered protectivedevices, un-metered protective devices, and metered devices (PMDs); anupstream to downstream module configured to assess condition of eachmetered protective device, un-metered protective device, and metereddevice (PMD), starting from a feeder circuit breaker towards feederdownstream, to estimate a tripped protective device and a last metereddevice upstream of a fault; and a downstream to upstream moduleconfigured to assess outaged electric loads and elements towards networkupstream to find the common interrupting protective device.
 2. Thesystem of claim 1, wherein the estimated tripped protective device andthe last metered device upstream of the fault, and the commoninterrupting protective device are merged to estimate one or morefaulted areas.
 3. The system of claim 1, wherein the one or more inputdata to the fault detection module comprise online data.
 4. The systemof claim 3, wherein the online data comprise one or more of condition,fault indication, reclosing stage, crew feedback and customer call data.5. The system of claim 1, wherein the condition estimation modulefurther receives online data and offline data as input.
 6. The system ofclaim 5, wherein the online data comprise one or more of condition,fault indication, reclosing stage, crew feedback and customer call data.7. The system of claim 5, wherein the offline data comprise one or moreof connectivity data and high level operational behavior of the PMDs. 8.The system of claim 7, wherein the high level operational behaviorcomprises one or more of observability, reclosability, faultinterruptability and switching capability.
 9. The system of claim 1,wherein the condition is one of Energized, Close_Hot, Close, Close_Dead,Open_Hot, Open, Open_Dead, and Unknown.
 10. The system of claim 1,wherein the condition estimation module further configured to: (1)determine one or more child tables for the PMDs; (2) determine one ormore parent tables for the PMDs; (3) apply one or more first rules tothe one or more parent tables to estimate condition of a parent PMD; (4)apply one or more second rules to the one or more child tables toestimate condition of a child PMD; (5) compare the estimated conditionof the parent PMD and the estimated condition of the child PMD; and upondetermining that the estimated condition of the parent PMD and theestimated condition of the child PMD is not the same, repeat steps (1)to (5).
 11. A method for estimating faulted area in an electricdistribution system, comprising: estimating, by a fault detectionmodule, based on one or more input data, if a new faulted areaestimation process is required; estimating, by a condition estimationmodule, condition of metered protective devices, un-metered protectivedevices, and metered devices (PMDs); assessing, by an upstream todownstream module, condition of each metered protective device,un-metered protective device, and metered device (PMD), starting from afeeder circuit breaker towards feeder downstream, to estimate a trippedprotective device and a last metered device upstream of a fault; andassessing, by a downstream to upstream module, outaged electric loadsand elements towards network upstream to find the common interruptingprotective device.
 12. The method of claim 11, further merging theestimated tripped protective device and the last metered device upstreamof the fault, and the common interrupting protective device to estimateone or more faulted areas.
 13. The method of claim 11, wherein the oneor more input data to the fault detection module comprise online data.14. The method of claim 13, wherein the online data comprise one or moreof condition, fault indication, reclosing stage, crew feedback andcustomer call data.
 15. The method of claim 11, further receiving, bythe condition estimation module, online data and offline data as input.16. The method of claim 15, wherein the online data comprise one or moreof condition, fault indication, reclosing stage, crew feedback andcustomer call data.
 17. The method of claim 15, wherein the offline datacomprise one or more of connectivity data and high level operationalbehavior of the PMDs.
 18. The method of claim 17, wherein the high leveloperational behavior comprises one or more of observability,reclosability, fault interruptability and switching capability.
 19. Themethod of claim 11, further, by the condition estimation module: (1)determining one or more child tables for the PMDs; (2) determining oneor more parent tables for the PMDs; (3) applying one or more first rulesto the one or more parent tables to estimate condition of a parent PMD;(4) applying one or more second rules to the one or more child tables toestimate condition of a child PMD; (5) comparing the estimated conditionof the parent PMD and the estimated condition of the child PMD; and upondetermining that the estimated condition of the parent PMD and theestimated condition of the child PMD is not the same, repeat steps (1)to (5).
 20. The method of claim 11, wherein the condition is one ofEnergized, Close_Hot, Close, Close_Dead, Open_Hot, Open, Open_Dead, andUnknown.